I don’t know anything about the “Pacific Islander lobby” but it’s not relevant here. The sentence here is clearly just not using the Oxford comma. Only the summary for journalists uses this construction. The actual abstract does not.

This paper breaks out Asian and Pacific Islander as separate ethnic groups in their data. You can see it in this summary and in the slightly more detailed data if you click through to the paper on JAMA.

(Actually they break out “Non-Hispanic Asian” and “Non-Hispanic Native Hawaiian or Other Pacific Islander”. The need to call out “non-Hispanic” on every ethnicity seems weird.)

That’s probably mostly true. Grouping ethnicities into labels that are useful seems like a difficult problem. Especially as risk factors can be both generic and cultural.